/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.testing;



import com.bff.gaia.unified.sdk.transforms.PTransform;

import com.bff.gaia.unified.sdk.transforms.SimpleFunction;

import com.bff.gaia.unified.sdk.transforms.windowing.PaneInfo;

import com.bff.gaia.unified.sdk.transforms.windowing.PaneInfo.Timing;

import com.bff.gaia.unified.sdk.values.PCollection;

import com.bff.gaia.unified.sdk.values.TypeDescriptor;

import com.bff.gaia.unified.sdk.values.ValueInSingleWindow;



import java.util.ArrayList;

import java.util.List;



/**

 * {@link PTransform PTransforms} which take an {@link Iterable} of {@link ValueInSingleWindow

 * ValueInSingleWindows} and outputs an {@link Iterable} of all values in the specified pane,

 * dropping the {@link ValueInSingleWindow} metadata.

 *

 * <p>Although all of the method signatures return SimpleFunction, users should ensure to set the

 * coder of any output {@link PCollection}, as appropriate {@link TypeDescriptor TypeDescriptors}

 * cannot be obtained when the extractor is created.

 */

final class PaneExtractors {

  private PaneExtractors() {}



  static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> onlyPane(

      PAssert.PAssertionSite site) {

    return new ExtractOnlyPane<>(site);

  }



  static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> onTimePane() {

    return new ExtractOnTimePane<>();

  }



  static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> finalPane() {

    return new ExtractFinalPane<>();

  }



  static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> nonLatePanes() {

    return new ExtractNonLatePanes<>();

  }



  static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> earlyPanes() {

    return new ExtractEarlyPanes<>();

  }



  static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> allPanes() {

    return new ExtractAllPanes<>();

  }



  private static class ExtractOnlyPane<T>

      extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {

    private final PAssert.PAssertionSite site;



    private ExtractOnlyPane(PAssert.PAssertionSite site) {

      this.site = site;

    }



    @Override

    public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {

      List<T> outputs = new ArrayList<>();

      for (ValueInSingleWindow<T> value : input) {

        if (!value.getPane().isFirst() || !value.getPane().isLast()) {

          throw site.wrap(

              String.format(

                  "Expected elements to be produced by a trigger that fires at most once, but got "

                      + "a value %s in a pane that is %s.",

                  value, value.getPane().isFirst() ? "not the last pane" : "not the first pane"));

        }

        outputs.add(value.getValue());

      }

      return outputs;

    }

  }



  private static class ExtractOnTimePane<T>

      extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {

    @Override

    public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {

      List<T> outputs = new ArrayList<>();

      for (ValueInSingleWindow<T> value : input) {

        if (value.getPane().getTiming().equals(Timing.ON_TIME)) {

          outputs.add(value.getValue());

        }

      }

      return outputs;

    }

  }



  private static class ExtractFinalPane<T>

      extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {

    @Override

    public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {

      List<T> outputs = new ArrayList<>();

      for (ValueInSingleWindow<T> value : input) {

        if (value.getPane().isLast()) {

          outputs.add(value.getValue());

        }

      }

      return outputs;

    }

  }



  private static class ExtractAllPanes<T>

      extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {

    @Override

    public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {

      List<T> outputs = new ArrayList<>();

      for (ValueInSingleWindow<T> value : input) {

        outputs.add(value.getValue());

      }

      return outputs;

    }

  }



  private static class ExtractNonLatePanes<T>

      extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {

    @Override

    public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {

      List<T> outputs = new ArrayList<>();

      for (ValueInSingleWindow<T> value : input) {

        if (value.getPane().getTiming() != PaneInfo.Timing.LATE) {

          outputs.add(value.getValue());

        }

      }

      return outputs;

    }

  }



  private static class ExtractEarlyPanes<T>

      extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {

    @Override

    public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {

      List<T> outputs = new ArrayList<>();

      for (ValueInSingleWindow<T> value : input) {

        if (value.getPane().getTiming() == PaneInfo.Timing.EARLY) {

          outputs.add(value.getValue());

        }

      }

      return outputs;

    }

  }

}